This invention relates to a flash memory device.
In recent years, flash memory devices have become common that employs flash memories allowing high-speed read/write as storage media. Advancement in miniaturization of flash memories lowers the prices of flash memory devices but increases the error rate of the stored data. For this reason, the flash memory devices need to perform data recovery with an error correction function. However, data retrieved in a single read may include errors more than the limit of correction, depending on the condition of the flash memory chip.
To increase the reliability, flash memory devices have a read retry function that re-reads data with a parameter different from the one used in the previous read. The read retry function can raise the possibility to read data successfully by reducing the errors in the data in a single read to less than the limit of correction. For example, US 2013/0238836 A discloses that a processor searches for an appropriate read parameter and instructs a flash memory interface to transfer the read parameter.
Patent Literature 1: US 2013/0238836 A